Flame-retardant wall insulation board and production process thereof

Abstract

The invention belongs to the technical field of wall insulation materials, and provides a flame-retardant wall insulation board and a production process thereof. According to the invention, a composite matrix is constructed through a polyurethane prepolymer and bisphenol A epoxy resin, and an interpenetrating network is formed by crosslinking an epoxy group and isocyanate, so that the mechanical strength is improved; and a quaternary flame-retardant system coated with silica sol is adopted, so that gas phase-condensed phase synergistic flame retardance is realized. According to the preparation process, step curing is combined with axial vibration to promote filler arrangement, cell collapse is avoided, low-temperature ultrasonic dispersion guarantees uniform mixing of the nano filler, and the interface adhesion is enhanced through the correlative design of the embossing depth and the plate thickness. The flame retardant property of the obtained product reaches the V-0 level and far exceeds the requirement of the national standard B1 level, the heat conductivity coefficient is superior to that of mainstream products in the market, and the product has excellent heat preservation and heat insulation performance and high safety and has remarkable application value in the field of building heat preservation.

Description

Technical Field

[0001] The present invention relates to the technical field of wall insulation materials, in particular to a flame-retardant wall insulation board and a production process thereof. Background Art

[0002] In the fields of building energy conservation and fire safety, flame-retardant polyurethane insulation boards are widely used due to their excellent thermal insulation properties. However, these insulation boards currently face several technical bottlenecks that need to be overcome.

[0003] In terms of material structure, existing flame-retardant polyurethane insulation boards are mostly based on a single matrix structure, making their mechanical properties difficult to meet the requirements of complex application scenarios. They are prone to deformation under long-term loads, seriously affecting their service life and building safety. Regarding flame retardancy, traditional flame retardant systems often use a conventional model of compounding flame retardants. However, due to the limited dispersibility and synergistic effects of flame retardants, the flame retardant efficiency is low, and the material oxygen index barely reaches the critical value required by industry standards, making it difficult to meet increasingly stringent fire protection regulations.

[0004] In the production process, the traditional mechanical mixing process can easily cause the agglomeration of nano-scale flame retardant fillers during the compounding process of flame retardant fillers and resin matrix, and at the same time cause damage to the sheet structure, resulting in a significant decrease in the thermal insulation performance of the insulation board; the static constant temperature method used in the curing and molding stage leads to incomplete decomposition of the foaming agent, forming a coarse bubble structure, which not only reduces the closed-cell rate of the board and weakens the thermal insulation performance, but also causes molten dripping in the combustion test, making it impossible to pass the high-level fire safety certification.

[0005] In addition, the surface of existing flame-retardant polyurethane insulation boards lacks effective interface reinforcement design, and the interface bonding strength is insufficient when bonding with the building matrix, which poses a risk of easy peeling; flame-retardant components that have not been specially modified have poor stability in humid and hot environments and are prone to migration and precipitation, causing the fire-retardant performance of the boards to rapidly decay over time, making it difficult to achieve long-term and stable flame-retardant effects.

[0006] In summary, how to solve the technical difficulties of existing flame-retardant polyurethane insulation boards in terms of mechanical properties, flame retardant efficiency, production process and interface stability has become a key technical issue that urgently needs to be improved in this field. Summary of the Invention

[0007] The purpose of the present invention is to overcome the problems existing in the prior art and provide a flame retardant wall insulation board and a production process thereof.

[0008] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0009] The present invention provides a flame-retardant wall insulation board, comprising the following raw materials in parts by weight:

[0010] 50-70 parts of polyurethane prepolymer, 15-30 parts of modified ammonium polyphosphate, 10-20 parts of bisphenol A epoxy resin, 5-15 parts of melamine cyanurate, 3-10 parts of expanded graphite, 8-15 parts of nano-aluminum hydroxide, 2-8 parts of polyolefin microsphere foaming agent, and 1-3 parts of silane coupling agent.

[0011] Furthermore, the modified ammonium polyphosphate is type II ammonium polyphosphate with a polymerization degree of ≥1000 and coated with silica sol.

[0012] Furthermore, the epoxy equivalent of the bisphenol A epoxy resin is 180-220 g / eq.

[0013] Furthermore, the particle size of the expanded graphite is 80-200 mesh, and the expansion ratio is ≥200 mL / g.

[0014] Furthermore, the polyolefin microsphere foaming agent is thermoplastic acrylate / acrylonitrile copolymer microspheres with an average particle size of 20-50 μm and an activation temperature of 120-150° C.

[0015] The present invention provides a production process for the flame-retardant wall insulation board, comprising the following steps:

[0016] S1, mixing modified ammonium polyphosphate, melamine cyanurate, expanded graphite and nano-aluminum hydroxide to obtain a premix A;

[0017] S2, mixing the polyurethane prepolymer, bisphenol A epoxy resin and silane coupling agent under vacuum stirring to obtain a premix B;

[0018] S3, ultrasonically dispersing and mixing the premix A, premix B, and polyolefin microsphere foaming agent to obtain a mixture;

[0019] S4. The mixture is injected into a mold and then cured. After curing, the mixture is demoulded and double-sided embossing is performed to obtain a flame retardant wall insulation board.

[0020] Furthermore, in step S1, the mixing temperature is 60-80° C., and the mixing time is 10-20 min.

[0021] Furthermore, in step S2, the vacuum degree of the vacuum stirring and mixing is ≤-0.08 MPa, and the time of the vacuum stirring and mixing is 5 to 15 minutes.

[0022] Furthermore, in step S3, the power of ultrasonic dispersion mixing is 800-1200 W, the frequency is 20-40 kHz, the amplitude is 0.1-0.5 mm, the temperature is 40-50° C., and the time is 10-30 min.

[0023] Furthermore, in step S4, the curing pressure is 0.5~2MPa, and the curing process is divided into three stages. The temperature of the first stage is 70~90℃, and the insulation time is 50~70min; the temperature of the second stage is 100~120℃, and the insulation time is 100~150min; the temperature of the third stage is 130~150℃, and the insulation time is 80~100min.

[0024] It can be seen from the above technical solution that compared with the prior art, the beneficial effects of the present invention are as follows:

[0025] 1. The present invention uses a polyurethane prepolymer and bisphenol A epoxy resin to form a composite matrix, forming a unique interpenetrating network structure through cross-linking of epoxy groups and isocyanates. Compared with a single polyurethane system, the mechanical strength of the insulation board is significantly improved, and it can better withstand external pressure and impact, ensuring structural stability during use. At the same time, the quaternary flame retardant system of silica sol-coated ammonium polyphosphate, melamine cyanurate, expanded graphite and nano-aluminum hydroxide breaks through the limitations of traditional flame retardant technology and achieves gas-phase-condensed phase synergistic flame retardancy. Compared with ternary flame retardants, it greatly enhances the flame retardant effect and provides more reliable protection for building fire safety.

[0026] 2. The present invention adopts a step-by-step curing combined with an axial vibration process to replace the traditional static curing. The vibration effect promotes the directional arrangement of the filler, optimizes the internal structure of the material, and the step-by-step heating method effectively avoids the collapse of the bubbles, ensuring the good foaming structure and thermal insulation performance of the insulation board; low-temperature ultrasonic dispersion technology replaces mechanical mixing, which can not only ensure the uniform dispersion of nanofillers, but also will not destroy the microsphere structure, significantly improving the uniformity and stability of the material mixing; the embossing depth is designed to be related to the board thickness, while improving the interface adhesion, maintaining the stability of the thermal insulation performance, enhancing the bonding strength between the insulation board and the wall, preventing it from falling off, and extending the service life.

[0027] 3. The flame retardant performance of the product prepared by the present invention reaches an extremely high level of oxygen index, achieving V-0 flame retardancy, far exceeding the national standard GB 8624-2012 B1 level requirement. When a fire occurs, it can effectively suppress the spread of fire and ensure the safety of life and property; the thermal conductivity coefficient is significantly lower than that of the mainstream flame-retardant insulation board on the market, and it has excellent thermal insulation performance, which can greatly reduce building energy consumption, help energy conservation and emission reduction, and demonstrate excellent application value and market competitiveness in the field of building insulation. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 The present invention provides a flow chart for preparing a flame-retardant wall insulation board. DETAILED DESCRIPTION

[0029] The present invention provides a flame-retardant wall insulation board, comprising the following raw materials in parts by weight:

[0030] 50-70 parts of polyurethane prepolymer, 15-30 parts of modified ammonium polyphosphate, 10-20 parts of bisphenol A epoxy resin, 5-15 parts of melamine cyanurate, 3-10 parts of expanded graphite, 8-15 parts of nano-aluminum hydroxide, 2-8 parts of polyolefin microsphere foaming agent, and 1-3 parts of silane coupling agent.

[0031] In the present invention, the amount of the polyurethane prepolymer is preferably 55 to 65 parts, more preferably 60 parts.

[0032] In the present invention, the amount of modified ammonium polyphosphate is preferably 18 to 25 parts, more preferably 20 parts.

[0033] In the present invention, the amount of bisphenol A type epoxy resin used is preferably 15 parts.

[0034] In the present invention, the amount of melamine cyanurate used is preferably 10 parts.

[0035] In the present invention, the amount of expanded graphite used is preferably 5 parts.

[0036] In the present invention, the amount of nano aluminum hydroxide used is preferably 10 parts.

[0037] In the present invention, the amount of the polyolefin microsphere foaming agent is preferably 5 parts.

[0038] In the present invention, the amount of the silane coupling agent is preferably 2 parts.

[0039] In the present invention, the modified ammonium polyphosphate is type II ammonium polyphosphate with a polymerization degree of ≥1000 that is coated with silica sol.

[0040] In the present invention, the epoxy equivalent of the bisphenol A epoxy resin is 180 to 220 g / eq, preferably 200 g / eq.

[0041] In the present invention, the particle size of the expanded graphite is 80-200 mesh, preferably 100-150 mesh; and the expansion ratio is ≥200 mL / g.

[0042] In the present invention, the polyolefin microsphere foaming agent is thermoplastic acrylate / acrylonitrile copolymer microspheres with an average particle size of 20-50 μm, preferably 30-40 μm; and an activation temperature of 120-150° C., preferably 130-140° C.

[0043] In the present invention, the thickness of the flame retardant wall insulation board is 20-50 mm.

[0044] The present invention provides a production process for the flame-retardant wall insulation board, comprising the following steps:

[0045] S1, mixing modified ammonium polyphosphate, melamine cyanurate, expanded graphite and nano-aluminum hydroxide to obtain a premix A;

[0046] S2, mixing the polyurethane prepolymer, bisphenol A epoxy resin and silane coupling agent under vacuum stirring to obtain a premix B;

[0047] S3, ultrasonically dispersing and mixing the premix A, premix B, and polyolefin microsphere foaming agent to obtain a mixture;

[0048] S4. The mixture is injected into a mold and then cured. After curing, the mixture is demoulded and double-sided embossing is performed to obtain a flame retardant wall insulation board.

[0049] In the present invention, in step S1, the mixing temperature is 60-80°C, preferably 65-75°C, and more preferably 70°C; the mixing time is 10-20 minutes, preferably 15 minutes.

[0050] In the present invention, in step S2, the vacuum degree of vacuum stirring and mixing is ≤-0.08 MPa, and the time of vacuum stirring and mixing is 5 to 15 minutes, preferably 10 minutes.

[0051] In the present invention, in step S3, the power of ultrasonic dispersion mixing is 800~1200W, preferably 900~1000W; the frequency is 20~40kHz, preferably 25~35kHz, more preferably 30kHz; the amplitude is 0.1~0.5mm, preferably 0.2~0.4mm; the temperature is 40~50℃, preferably 45℃; and the time is 10~30min, preferably 15~25min, more preferably 20min.

[0052] In the present invention, in step S4, the curing pressure is 0.5~2MPa, preferably 1~1.5MPa; the curing process is divided into three stages, the temperature of the first stage is 70~90℃, preferably 80℃, and the insulation time is 50~70min, preferably 60min; the temperature of the second stage is 100~120℃, preferably 110℃, and the insulation time is 100~150min, preferably 120~130min; the temperature of the third stage is 130~150℃, preferably 140℃, and the insulation time is 80~100min, preferably 90min.

[0053] In the present invention, in step S4, the embossing treatment temperature is 70-90°C, preferably 75-85°C, and more preferably 80°C; the embossing depth is 8-12% of the plate thickness, preferably 10%; and a staggered diamond-shaped concave-convex structure is formed.

[0054] The technical principle of this invention is the epoxy-isocyanate autocatalytic reaction mechanism. The reactive isocyanate groups (-NCO) enriched at the ends of the polyurethane prepolymer and the epoxy groups (-CH(O)CH-) of the bisphenol A epoxy resin undergo spontaneous and gradual polymerization under heating conditions. This is essentially due to the nucleophilic attack of the -NCO groups by the oxygen anions generated by the thermal ring opening of the epoxy groups. This process does not require an external catalyst due to the following reasons:

[0055] 1. Thermally activated ring-opening mechanism: When the system temperature rises above 110°C (significantly higher than the epoxy ring-opening activation energy threshold of 85 kJ / mol), the epoxy ring tension is released, resulting in homolytic cleavage of the CO bond and the generation of highly reactive oxygen anions.

[0056] 2. Intramolecular synergistic effect: The trace amount of urethane bonds (-NHCOO-) remaining in the polyurethane prepolymer molecular chain can act as a proton donor, stabilizing the ring-opening transition state through hydrogen bonds and reducing the reaction energy barrier;

[0057] 3. Nanofiller surface catalysis: The Al-OH groups exposed on the surface of nano-aluminum hydroxide have weak Lewis acidity, which can polarize the CO bond of the epoxy group and promote the ring-opening reaction rate by 2-3 orders of magnitude.

[0058] The step curing process of the present invention is the key to achieving a two-phase continuous network:

[0059] The first stage: polyurethane prepolymer self-polymerizes to form a primary cross-linking network, at which time the epoxy group has not yet been activated;

[0060] The second stage: the epoxy ring opens and reacts with the remaining -NCO to generate oxazolidinone crosslinking points in situ in the polyurethane network, forming a semi-interpenetrating network;

[0061] The third stage: The unreacted epoxy groups are homopolymerized under the catalysis of nano-aluminum hydroxide to form independent epoxy domains (domain size ≈ 50 nm) that run through the polyurethane network, and finally construct a fully interpenetrating network.

[0062] The technical solutions provided by the present invention are described in detail below with reference to the embodiments, but they should not be construed as limiting the scope of protection of the present invention.

[0063] Example 1

[0064] The raw material proportions of the present embodiment are as follows:

[0065] 60 parts of polyurethane prepolymer, 20 parts of modified ammonium polyphosphate (silica sol coated, degree of polymerization ≥1000), 15 parts of bisphenol A epoxy resin (epoxy equivalent 200g / eq), 10 parts of melamine cyanurate, 5 parts of expanded graphite (100 mesh, expansion ratio ≥200mL / g), 10 parts of nano-aluminum hydroxide, 5 parts of polyolefin microsphere foaming agent (particle size 30μm, activation temperature 135℃), and 2 parts of silane coupling agent (KH-550).

[0066] The preparation process is as follows:

[0067] Reference Figure 1 Modified ammonium polyphosphate, melamine cyanurate, expanded graphite, and nano-aluminum hydroxide were mixed at 70°C for 15 minutes to obtain premix A. A polyurethane prepolymer, epoxy resin, and silane coupling agent were stirred under vacuum at -0.08 MPa for 10 minutes to obtain premix B. Premixes A and B were then ultrasonically dispersed with a blowing agent at 900 W, 30 kHz, an amplitude of 0.3 mm, and 45°C for 20 minutes to obtain a mixed material. The mixed material was injected into a mold, pressurized to 1.2 MPa, and cured in three stages: the first stage at 80°C for 60 minutes; the second stage at 110°C for 125 minutes; and the third stage at 140°C for 90 minutes. After curing, the material was demolded and then double-sided embossed at 80°C to a depth of 10% of the thickness, forming a staggered diamond-shaped concave-convex structure.

[0068] Example 2

[0069] The raw material proportions of the present embodiment are as follows:

[0070] 55 parts of polyurethane prepolymer, 25 parts of modified ammonium polyphosphate (silica sol coated, degree of polymerization ≥1000), 18 parts of bisphenol A epoxy resin (epoxy equivalent 200g / eq), 12 parts of melamine cyanurate, 8 parts of expanded graphite (100 mesh, expansion ratio ≥200mL / g), 13 parts of nano-aluminum hydroxide, 6 parts of polyolefin microsphere foaming agent (particle size 30μm, activation temperature 135℃), and 2.5 parts of silane coupling agent (KH-550).

[0071] The preparation process is as follows:

[0072] Modified ammonium polyphosphate, melamine cyanurate, expanded graphite, and nano-aluminum hydroxide were mixed at 70°C for 20 minutes to produce premix A. A polyurethane prepolymer, epoxy resin, and silane coupling agent were stirred under vacuum at -0.08 MPa for 10 minutes to produce premix B. Premix A and B were then ultrasonically dispersed with a blowing agent at 1000 W, 30 kHz, an amplitude of 0.3 mm, and 45°C for 25 minutes to produce a composite. The composite was injected into a mold, pressurized to 1.5 MPa, and cured in three stages: the first stage: 80°C for 60 minutes; the second stage: 115°C for 140 minutes; and the third stage: 140°C for 90 minutes. After curing, the composite was demolded and then double-sided embossed at 80°C to a depth of 10% of the thickness, forming a staggered diamond-shaped concave-convex structure.

[0073] Example 3

[0074] The raw material proportions of the present embodiment are as follows:

[0075] 50 parts of polyurethane prepolymer, 18 parts of modified ammonium polyphosphate (silica sol coated, degree of polymerization ≥1000), 12 parts of bisphenol A epoxy resin (epoxy equivalent 200g / eq), 8 parts of melamine cyanurate, 4 parts of expanded graphite (100 mesh, expansion ratio ≥200mL / g), 8 parts of nano-aluminum hydroxide, 3 parts of polyolefin microsphere foaming agent (particle size 30μm, activation temperature 135℃), and 1.5 parts of silane coupling agent (KH-550).

[0076] The preparation process is as follows:

[0077] Modified ammonium polyphosphate, melamine cyanurate, expanded graphite, and nano-aluminum hydroxide were mixed at 65°C for 10 minutes to obtain premix A. A polyurethane prepolymer, epoxy resin, and silane coupling agent were stirred under vacuum at -0.08 MPa for 10 minutes to obtain premix B. Premix A and B were then ultrasonically dispersed with a blowing agent at 800 W, 30 kHz, an amplitude of 0.3 mm, and 40°C for 15 minutes to obtain a composite material. The composite material was injected into a mold, pressurized to 0.8 MPa, and cured in three stages: the first stage at 75°C for 55 minutes; the second stage at 105°C for 110 minutes; and the third stage at 140°C for 90 minutes. After curing, the material was demolded and then double-sided embossed at 80°C to a depth of 10% of the thickness, forming a staggered diamond-shaped concave-convex structure.

[0078] Example 4

[0079] The raw material proportions of the present embodiment are as follows:

[0080] 65 parts of polyurethane prepolymer, 20 parts of modified ammonium polyphosphate (silica sol coated, degree of polymerization ≥1000), 20 parts of bisphenol A epoxy resin (epoxy equivalent 200g / eq), 15 parts of melamine cyanurate, 6 parts of expanded graphite (100 mesh, expansion ratio ≥200mL / g), 12 parts of nano-aluminum hydroxide, 8 parts of polyolefin microsphere foaming agent (particle size 40μm, activation temperature 135℃), and 3 parts of silane coupling agent (KH-550).

[0081] The preparation process is as follows:

[0082] Modified ammonium polyphosphate, melamine cyanurate, expanded graphite, and nano-aluminum hydroxide were mixed at 65°C for 10 minutes to obtain premix A. A polyurethane prepolymer, epoxy resin, and silane coupling agent were stirred under vacuum at -0.08 MPa for 5 minutes to obtain premix B. Premix A and B were then ultrasonically dispersed with a blowing agent at 1200 W, 35 kHz, an amplitude of 0.4 mm, and 40°C for 15 minutes to obtain a composite material. The composite material was injected into a mold, pressurized to 0.8 MPa, and cured in three stages: the first stage at 75°C for 55 minutes; the second stage at 105°C for 110 minutes; and the third stage at 150°C for 80 minutes. After curing, the material was demolded and then double-sided embossed at 80°C to a depth of 10% of the thickness, forming a staggered diamond-shaped concave-convex structure.

[0083] Example 5

[0084] The raw material proportions of the present embodiment are as follows:

[0085] 70 parts of polyurethane prepolymer, 30 parts of modified ammonium polyphosphate (silica sol coated, degree of polymerization ≥1000), 10 parts of bisphenol A epoxy resin (epoxy equivalent 200g / eq), 5 parts of melamine cyanurate, 10 parts of expanded graphite (100 mesh, expansion ratio ≥200mL / g), 15 parts of nano-aluminum hydroxide, 2 parts of polyolefin microsphere foaming agent (particle size 40μm, activation temperature 135℃), and 1 part of silane coupling agent (KH-550).

[0086] The preparation process is as follows:

[0087] Modified ammonium polyphosphate, melamine cyanurate, expanded graphite, and nano-aluminum hydroxide were mixed at 80°C for 20 minutes to produce premix A. A polyurethane prepolymer, epoxy resin, and silane coupling agent were stirred under vacuum at -0.08 MPa for 5 minutes to produce premix B. Premix A and B were then ultrasonically dispersed with a blowing agent at 1200 W, 35 kHz, an amplitude of 0.4 mm, and 40°C for 15 minutes to produce a composite. The composite was injected into a mold, pressurized to 2 MPa, and cured in three stages: the first stage: 90°C for 70 minutes; the second stage: 105°C for 110 minutes; and the third stage: 150°C for 80 minutes. After curing, the composite was demolded and then double-sided embossed at 90°C to a depth of 10% of the thickness, creating a staggered diamond-shaped concave-convex structure.

[0088] The performance tests of the products prepared in Examples 1 to 5 are shown in Table 1.

[0089] Table 1 Performance test standards and results

[0090] category Oxygen index Thermal conductivity W / (m·K) Compression strength (MPa) Vertical combustion level Implementation standards GB / T 2406-2008 GB / T 10295-2008 GB / T 8813-2020 UL 94 Example 1 42% 0.026 0.31 V-0 Example 2 39% 0.029 0.26 V-0 Example 3 40% 0.032 0.25 V-0 Example 4 40% 0.031 0.30 V-0 Example 5 38% 0.028 0.30 V-0

[0091] As shown in Table 1, the insulation board has an oxygen index of ≥38%, which is over 30% higher than traditional insulation materials. This demonstrates excellent flame retardancy and significantly slows flame spread when exposed to open flames, effectively reducing the risk of the material itself becoming a fire source in a fire accident. Its thermal conductivity is ≤0.032 W / (m·K), an industry-leading level, significantly reducing heat conduction efficiency. Compared to conventional insulation boards of the same thickness, it achieves higher thermal insulation performance, effectively reducing building energy consumption. Its compressive strength is ≥0.25 MPa, ensuring the board's excellent structural stability during transportation, installation, and long-term use. Even under high-intensity external forces, it maintains its intact physical form and thermal insulation properties. Its vertical combustion rating reaches V-0, a stringent international standard certification that means the board self-extinguishes within a very short time in vertical combustion tests without producing flaming drips. This effectively blocks the path of fire spread, significantly improving the building's fire safety rating and providing dual protection for energy conservation and fire safety.

[0092] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as within the scope of protection of the present invention.

Claims

1. A flame retardant wall insulation board, characterized in that: The invention comprises the following raw materials in parts by weight: 50-70 parts of polyurethane prepolymer, 15-30 parts of modified ammonium polyphosphate, 10-20 parts of bisphenol A epoxy resin, 5-15 parts of melamine cyanurate, 3-10 parts of expanded graphite, 8-15 parts of nano-aluminum hydroxide, 2-8 parts of polyolefin microsphere foaming agent, and 1-3 parts of silane coupling agent.

2. The flame retardant wall insulation board according to claim 1, characterized in that: The modified ammonium polyphosphate is type II ammonium polyphosphate coated with silica sol and having a polymerization degree of ≥1000.

3. The flame retardant wall insulation board according to claim 2, characterized in that: The epoxy equivalent of the bisphenol A epoxy resin is 180-220 g / eq.

4. The flame retardant wall insulation board according to claim 3, characterized in that: The particle size of the expanded graphite is 80-200 mesh, and the expansion ratio is ≥200 mL / g.

5. The flame retardant wall insulation board according to claim 2 or 4, characterized in that: The polyolefin microsphere foaming agent is thermoplastic acrylate / acrylonitrile copolymer microspheres with an average particle size of 20-50 μm and an activation temperature of 120-150° C.

6. The production process of the flame-retardant wall insulation board according to any one of claims 1 to 5, characterized in that: The following steps are involved: S1, mixing modified ammonium polyphosphate, melamine cyanurate, expanded graphite and nano-aluminum hydroxide to obtain a premix A; S2, mixing the polyurethane prepolymer, bisphenol A epoxy resin and silane coupling agent under vacuum stirring to obtain a premix B; S3, ultrasonically dispersing and mixing the premix A, premix B, and polyolefin microsphere foaming agent to obtain a mixture; S4. The mixture is injected into a mold and then cured. After curing, the mixture is demoulded and double-sided embossing is performed to obtain a flame retardant wall insulation board.

7. The production process of the flame retardant wall insulation board according to claim 6, characterized in that: In the above-mentioned S1, the mixing temperature is 60-80° C., and the mixing time is 10-20 min.

8. The production process of the flame retardant wall insulation board according to claim 7, characterized in that: In the above-mentioned S2, the vacuum degree of the vacuum stirring and mixing is ≤-0.08 MPa, and the time of the vacuum stirring and mixing is 5 to 15 minutes.

9. The production process of the flame retardant wall insulation board according to any one of claims 6 to 8, characterized in that: In the above-mentioned S3, the power of ultrasonic dispersion mixing is 800-1200 W, the frequency is 20-40 kHz, the amplitude is 0.1-0.5 mm, the temperature is 40-50° C., and the time is 10-30 min.

10. The production process of the flame retardant wall insulation board according to claim 9, characterized in that: In S4, the curing pressure is 0.5~2MPa, and the curing process is divided into three stages. The temperature of the first stage is 70~90℃, and the insulation time is 50~70min; the temperature of the second stage is 100~120℃, and the insulation time is 100~150min; the temperature of the third stage is 130~150℃, and the insulation time is 80~100min.

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